This invention relates to a half-round fluid film bearing having an improved locating notch configuration.
Half-round type fluid film bearings are used in widespread applications including nearly all of the crankshaft and connecting rod bearings used in conventional internal combustion engines for motor vehicles. These types of bearings have a pair of arc-shaped shell segments which are mounted to the engine block and a bearing cap and surrounds a cylindrical journal of the crankshaft. The bearings form a concave bearing crown area which faces the journal and have a pair of parting faces at their ends. Lubricant is forced under pressure to the clearance space between the bearing and the journal to provide an oil film which supports the journal and provides low rotational friction. Most half-round bearings in use today include a locating tab at one of the parting faces of each of the half-round bearing shells which project in a radially outward direction. These locating tabs are used to properly establish the positioning of the bearing shells until the supporting housings are completely assembled. The use of locating tabs has greatly reduced instances of bearing distress caused by misassembly.
The locating tab configuration presently in use for half-round bearings is typically a locally radially outwardly displaced segment of the bearing material at the shell parting face which leaves a channel formed in the crown surface of the bearing shell. Half-round bearings are typically manufactured beginning with flat sheet stock made up of a number of layers of various materials which is formed to the half-round configuration with the locating tab. The parting faces of the bearing shell are thereafter broached to control the arc length of the bearing. Due to the local discontinuity in one of the parting faces of the bearing caused by the existence of the locating tab, the broaching tools can sometimes leave burrs in the area of the locating tab which can prevent the proper seating of the bearing shell in the housing. The crown surface is broached to a predetermined thickness called the bearing wall. In the channel formed in the crown surface of the bearing shell, the wall broaching operation sometimes causes a sliver of lining material to be generated. Removal of this sliver is difficult and if the sliver breaks free can lead to premature bearing wear. Accordingly, there is a need to provide an improved locating tab configuration for half-round bearings which alleviates the problems of sharp edges presented by the locating tab and slivers in the channel.
The improved half-round bearing in accordance with this invention achieves the above mentioned desirable features through the use of a coining method which locally upsets the bearing metal to form a radially outwardly projecting tab, while maintaining the integrity of the bearing crown surface in that area. In a subsequent broaching operation, the bearing material at the parting face is trimmed such that the notch resulting from the coining procedure is removed, leaving no burrs in the area of the locating tab. Slivers are prevented by the integrity of the bearing crown surface. These changes overcome the undesirable features of bearing designs according to the prior art.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings.